Wednesday, June 20, 2012

The GUIDE: A Problem of Mind and Brain

A friend and reader recently asked permission to quote this blog for a philosophy class and further asked: "What are the differences between the mind and the brain? ... I would like to request a one to two sentence quote from you
summing up your opinion on those differences..."

My quick response is as follows:

"The problem of mind and brain has been with us ever since scientists
first decided that we thought with that organ in our heads instead of
our hearts. It is possible for the neuroscientist to define all of the
activity of the brain and brain cells, and even trace all of the steps
through which information flows, and still not understand how such
information becomes a 'thought'. We know that there are many 'emergent'
properties which arise from neural activity that cannot be predicted
entirely from study of neurons and brain areas, but it is still only our
best guess that these properties constitute what we think of as 'the
mind'."

Vonn - I thank you for the opportunity to put my thoughts in order, and figured you may appreciate if I were to put this in just a bit more perspective.

What is the Mind? And where is it located? It's a very interesting question, and gets a little bit into psychology and Dr. Travis Taylor's quantum theory of the mind -that's a bit far afield for today's blog, but considering that I am currently attending a professional neuroprosthetics meeting, it is appropriate to my attitude at this time.

As neuroscientists, my colleagues and I know an awful lot about how the brain works. We can trace information such as a sight, sound or touch into the brain, follow the various processing stages and relays, and even trace the resulting outputs in terms of motor / muscle movement outputs. Such studies are direct in that we can directly translate between the activity of a given neuron and the information encoded by that neuron or its brain area. For other functions, the function tracing is much less direct, and much of what we know is due to understanding deficits which occur folowing brain damage. We can specify which brain areas underlie emotion, motivation, memory, expectancy, etc. by seeing what deficits occur when those brain areas are damaged by stroke, epilepsy or head injury. Likewise, we can produce what is knowns a "reversible lesion" with drugs that anesthetize or inactivate small brain areas, then examine which functions are impaired when the inactivation occurs.

However, none of this answers the question of how "thoughts" arise in those same brain structure: for example - we know that shining a 488 nm wavelength light on the retina activates "blue" receptors, and this in turn activates "blue" representation in visual cortex. We can also trace the contributing language and speech centers which associate the word "blue" with our ability to express the perception of the color. However, none of these functions explain not only how we perceive an abstract concept such as color, but how we can continue to identifying that percept as "blue" even whether actual visual wavelength is altered by use of filters or sunglasses (try it sometime - even converting an image tobBlack-and-white, we can still tell when a color should be blue!).

What we do know is that networks of neurons exhibit what are called "emergent" properties - results that are not obvious from the simple physical properties of the components. An example was found early on in the science of artificial neural networks - computer programs which use neuron properties and connection principles for processing information. ANNs can be programmed to represent pictures, music and other complex information. Retrieving information from one of these ANN associative memory structures requires only a small portioned the original image. Incomplete or corrupted images can be converted to the appropriate image in the output. Thus the "emergent" property of the ANN is *pattern completion*.

There are many different forms of emergent properties, and an important one is the development of particular "states" of the brain. A "state" is a much broader pattern of brain activity that settles into a stable form that is repeatable when the conditions which evoke the state are repeated. One possibility is that the "states" may represent thoughts, but it is my own opinion that there are to few stable states and too many possible thoughts for there to be a one-to-one relationship.

So, where do "thoughts" come from, and what/where is the "mind"?

Physicist and SF writer Travis Taylor proposes that the "mind" is a emergent property not of physiology, but of quantum mechanics - that thoughts are quantum wave functions transduced by the neurofilament and microtubule structure of neurons. In Taylor's theory, the filaments act as antennas for quantum wave functions and account for not only individual mental activity, but also shared society memes, attraction and possibly racial memory. While I think the theory has many gaps from a neuroscience point of view and ignore the fact that microtubules and microfilaments occur in all cells and all animals, there is still the question of how emergent properties... well... emerge.

If I we're to engage in debate with Dr. Taylor, I would likely start by suggesting that he is looking at the wrong structure, neural activity depends on dendrites and synapses. Neural inputs are received at dendrites, integrated in the soma and transmitted to other neurons via axons. Neurotubules and neurofilaments are structural components, and the structure is less important to function than the synapse... But is it?

Neurofilaments control the structure of dendritic spines, and those spines contribute to the electrical strength with which a synapse responds to a signal. Neurotubules transport metabolic products throughout neurons, and are important to delivering the neurotransmitter molecules to storage in the axon terminal just short of the synapse. Is it really so farfetched to think that quantum wave functions could influence neural activity to the point where they alter not just the structure but the function of neurons leading to the emergence of what we call the "mind"?

My best answer at this time is that I/we just don't know, and that the question of mind (like that of the soul) is one that has no easy answer. It has particular importance in a future in which defining "human" will become blurred as we begin to apply bionics, genetics, cybernetics as well as advanced medical techniques. It also will not (can not) be answered by scientists alone, but requires the input of philosophy and religious scholars as well.

I just heard a speaker at my conference discuss the "sense of embodiment" in which it is possible to confuse the brain's sense of self by fooling the sensory inputs. It suggests that the mind is *not* limited to just the brain, and may lend credence to Taylor's quantum wave theory. we still don't know where all of the emergent properties come from, but it is certainly worth asking the question!

Until next time, take care of your brain, after all, a mind is a terrible thing... To waste.